Most PHP migration projects fail the same way. A parallel rewrite starts cleanly, runs for six months, reaches 80% complete — and stalls. The legacy system keeps receiving bug fixes. The two codebases diverge. The cutover date slips indefinitely. Nothing ships.
Legacy to Symfony is a book about avoiding that failure mode entirely.
It is a methodology-first guide to migrating a live PHP application to Symfony using the Strangler Fig pattern — routing traffic progressively from your legacy application to Symfony via Traefik, one vertical slice at a time, with no flag day and no big-bang cutover. The legacy system degrades gracefully. Progress is measurable and shippable from the first sprint.
What makes this different
The book is built around a specific, repeatable process — not principles. You will know exactly which container to spin up, which tool to run, which routing rule to add, and how to roll back if something goes wrong. The hard problems get full chapters: sharing a single database safely across two live applications, keeping users authenticated seamlessly as routes move across, converting a legacy view layer to Twig and Stimulus without a manual rewrite.
There is also a chapter on the psychology of leading a migration — because the engineer accountable for it will be under sustained pressure, and the decisions that kill projects are rarely technical.
The toolchain
The methodology is supported throughout by purpose-built tooling: migrator for codebase assessment and burn-down tracking, indoctrinate for database layer auditing and schema modernisation, and view-converter for automated template and JavaScript conversion. Each tool is introduced in context, with the commands and output you will actually see.
Available now
The book is available today on Leanpub at 95% completion — you can start reading immediately. The final version publishes on 15th June 2026 and all purchases include free updates.
Buy on Leanpub — DRM-free PDF, EPUB, and MOBI.